This study, the work of an international, multi-disciplinary team of experts coordinated by SEI, will be published as a peer-reviewed book later this year; this summary is being released to inform preparations for the Rio+20 Earth Summit.

The ocean faces a multitude of interconnected threats that is unprecedented in modern history. This book intends to help crystallise our understanding of the value of ocean services to humankind, allowing them to be accounted for as we plan for a future fraught with risk and uncertainty.

This book is a link in a chain rather than an end in itself. The conclusions and monetary figures it presents are not definitive – too much is yet unknown and uncertain for that – but are intended to contribute towards a new approach to ocean governance, one that is fully integrated and prioritised within the broader picture of social, environmental and economic policy. We critically need to go beyond the current approach of addressing (or ignoring!) one problem at a time. We must create management strategies that are aimed at optimising the sustainable benefits we can obtain from marine resources across scales from local to global, and in the face of several interacting and escalating threats.

The very chemical, thermodynamic and biological foundations of the ocean are being jeopardised by human activity, putting at risk marine ecosystems and services on which humankind so essentially depends. We need to be made aware of what we stand to lose if we continue to neglect the ocean and fail to adequately address global environmental change. This book hopes to guide policy-makers, accelerate the implementation of new management tools and systems, and – most importantly – encourage people to ask themselves what the oceans are really worth to them and to the future of our planet.